Gm. Walsh et al., HUMAN EOSINOPHILS PREFERENTIALLY SURVIVE ON TISSUE FIBRONECTIN COMPARED WITH PLASMA FIBRONECTIN, Clinical and experimental allergy, 25(11), 1995, pp. 1128-1136
Background Eosinophil-derived inflammatory mediators including cytokin
es are considered to be important in the pathogenesis of allergic infl
ammation. Fibronectin (Fn) has been shown to be a physiological trigge
r of autocrine cytokine production by human eosinophils. Fn is encoded
by a single gene, but alternate splicing of the primary RNA transcrip
t results in polypeptide diversity in a cell type-specific fashion. Th
us, tissue Fn contains approximately 50% more of the CS-1 cell binding
region recognized by the integrin alpha 4 beta 1 compared with plasma
Fn. Objective Since eosinophils are predominantly tissue-dwelling cel
ls we compared the effect of tissue and plasma Fn on eosinophil surviv
al in culture. Methods The viability and cytokine generation of eosino
phils (>99.9% pure) cultured for up to 4 days in 96 well plates coated
with tissue Fn, plasma Fn or BSA was compared. Results There was a si
gnificant difference in the ability of tissue Fn to support eosinophil
survival compared with plasma Fn (P < 0.01). Optimal survival with ti
ssue Fn was seen at 25 mu g/well (70% +/- 2.0% viability at 3 days vs
7% +/- 2.2% viability on BSA). Significant (P < 0.001) cell viability
on tissue Fn was observed for up to 4 days in culture (54% +/- 6.0%) c
ompared with BSA coated wells. Addition of autologous mononuclear cell
s (final concentration 0.5%, 1% or 2%) resulted in plasma Fn-dependent
eosinophil survival comparable to that of 99.9% pure eosinophils adhe
rent to tissue Fn. Tissue Fn-dependent survival was significantly inhi
bited by anti-interleukin-3, anti-granulocyte macrophage colony stimul
ating factor (GM-CSF) and anti-IL-5 monoclonal antibodies. Picogram qu
antities of these three cytokines were detected in supernatants from e
osinophils cultured for 3 days on tissue Fn using specific enzyme-link
ed immunosorbent assays (ELISAs). Eosinophil survival on tissue Fn was
significantly inhibited by anti-pr and alpha 4 beta 1 monoclonal anti
body (MoAb) and also by a MoAb specific for the CS-1 motif in the IIIC
S region of Fn. Conclusion These observations show preferential surviv
al of eosinophils cultured on tissue Fn as a result of alpha 4 beta 1-
dependent interaction with the CS-1 region of tissue Fn triggering aut
ocrine cytokine synthesis and release, thereby promoting their surviva
l and persistence within the tissues.